Asphaltic composition



United States Patent Q 3,014,809 ASPHALTIC COMPOSITION Robert P. Hoyt, Redondo Beach, and Gene C. Weber,

Hermosa Beach, Calif, assignors to Richfieid Oil Corporation, Los Angeies, Calif a corporation of Delaware No Drawing. Filed Oct. 2, 1953, Ser. No. 764,742 9 Claims. (Cl. 106-269) This invention relates to asphaltic compositions characterized by greater self-healing properties for a given melting point. More particularly, this invention relates to asphaltic compositions having higher softening points than generally associated with a given penetration.

The general physical and chemical characteristics of asphaltic materials have rendered them desirable for a variety of industrial uses. They have been used for example, in the production of pavements, roads, floors, paints, roofs, rust preventives, pipe coatings, etc.

It has often been theorized that if the characteristics of an asphalt could be altered to produce a material of high softening point but of little change in penetration the result could be a highly advantageous product. An asphalt of this type would be useful, for example, in the production of specialty products such as battery box sealants, water-resistant membranes for reservoirs and other applications requiring soft asphalts with low rates of flow and having self-healing properties.

The use of small amounts of heavy metal soaps as bonding agents in asphalts to improve the water resistance between the asphalts and solid aggregates, or the spreading tendency of asphalts upon wet surfaces is known. Heretofore, however, attempts to alter the characteristics of asphalts by the use of gelling agents to produce an asphalt having higher softening points than are generally associated with a given penetration have to the best of our knowledge been unsatisfactory.

The lithium salts of stearic acids are known, for example, as thickeners of lubricating oil and are commonly used in grease manufacturing and for gelling reduced crude oils such as road oils. See, for instance, Ashburn et al., 2,450,220, Matthews et al., 2,629,659 and 2,651,616, and Morgan 2,389,926. It has now been discovered that small amounts of a lithium stearate when incorporated into an asphaltic material produces a composition having a higher softening point than generally associated with a given penetration. The lithium stearate soap preferred for use in the present invention is lithium hydroxystearate, for instance 12, 10 or 9-hydroxystearates.

Asphaltic materials contemplated by the present invention are the viscous asphaltic materials commonly identified as penetration grade asphalts. Examples of these materials are oxidized and steam vacuum refined asphalts of petroleum residues and natural asphalts having a penetration at 77 F. of about 10 to 350.

The amount of lithium stearate incorporated in the asphalts of the present invention can be influenced by the oil content of the asphalt and the softening point desired for an asphalt of a given penetration. The higher penetration materials, for example, frequently require more of the additive than do the low penetration asphalts.

The three main constituents of the asphalts employed in the present invention are oils, resins and asphaltenes. Asphalts high in asphaltenes and resins and low in oils are categorized generally as low penetration asphalts. Conversely, the asphalts characterized by high oil content are known generally as high penetration asphalts. Since the amount of lithium stearate to be added can be influenced by the amount of oil in the asphalt, smaller quantities of the additive of the present invention will be sometimes needed for the low penetration asphalts than for the high penetration asphalts. Also, for any given penetration whether it be high or low, the desired softening point is another factor determining the amount of additive to be used. Consequently, concentrations varying anywhere from about 8.1 to 10 percent by weight are generally satisfactory for purposes of this invention.

The present invention will be further illustrated by the following examples.

EXAMPLE I An oxidized petroleum asphalt having a softening point of 219 F. and a penetration of 18 was blended with 5% of each of the substances listed below. The blending was accomplished by heating the asphalts to a temperature of 420 F., adding each substance slowly while stirring until a uniform product was obtained. It was found that above 400 F. the fluidity of the asphalts was not appreciably affected. However, as soon as the temperature fell below 380 a gelling effect was noted. The softening points and penetrations of the resulting blends are listed below:

Oxidized asphalt having the physical properties listed below was blended as in Example I with 0.5%, 1.0%

and 3.0% by weight of lithium 12-hydroxystearate. The test results are as follows:

Lithium Hydroxystearate, percent 0.0 0.5 1.0 3.0

Penetration at- 77 F 54 45 41 37 Softening Point, F 130 139 248 321 Ducility at 77 F 54 27 15 Flash Point, COO, F 480 520 540 540 EXAMPLE III Three grades of steam-vacuum refined paving asphalt (SRA) having the physical properties shown below were each blended with concentrations of 0.5, 1.0, 2.0 and 3.0 percents by weight of lithium 12-hydroxystearate. The test results are as follows:

38-50 PENETRATION SRA Lithium Hydroxystea'rate,

percent 0. 0. 1.0 2. 0 3. 0

Penetration at 77 F. 35 37 31 28 Penetration at 392 F. 10 12 12% 13 14 Penetration Index"... 26 33. 7 33. 7 42 Viscosity at 275 F1- 215 307 506 Viscosity at 400 F- 19 18 18 18 18 Softening Point, F- 127 13 140 142 147 Duetility at 77 F., 0 150+ 150+ 150+ 117 -100 PENETRATION SBA Lithium Hydr0xystearate,.

percent 0. 0 0. 5 1. 0 2.0 3. 0

Penetration at 77 F 91 87 80 7d 68 Penetration at 392 F 24 26 21 26 26 Penetration Index... 26. 2 29. 9 20. 3 37.0 38. 2 Viscosity at 275 F 119 145 223 369 3,000+ Viscosity at 400 F 15 10 16 16 Softening Point, F 113 113 118 192 205 'Duetility at 77 F., em 150+ 150+ 80 73 36 200-300 PENETRATION SRA Lithium Hydroxystearate,

percent 0. 0 0. 5 1. 0 2.0 3.0

Penetration at 77 F 237 226 182 174 181 Penetration at 39.2 F 62 59 59 50 51 Penetration Index. 26. 3 25. S 32.1 28. 7 28. 2 Viscosity at 275 F 02 S1 180 148 Viscosity at 400 F 13 13 13 13 13 Softening Point, 99 101 105 112 Ductility at 77 F., cm 1 01 41 27 21 The above data clearly demonstrates that an oxidized or steam refined asphalt of a given penetration can be altered to produce an asphalt of greatly increased softening point by the addition of small amounts of lithium hydroxystearate.

Examination of the results shows, in addition, that the penetration index is improved by the addition of lithium hydroxystearate, particularly in the 38-100 penetration stock as shown in Example III. Penetration index isan indication of the temperature susceptibility of the asphaltic material, that is, the higher the penetration index the lower the susceptibility of the material to temperature change. Penetration index is calculated by dividing the penetration value at 39.2 F. by the penetration value at 77 F. and multiplying the quotient by 100.

Example III also shows that the viscosity of the basic stock is not appreciably increased at temperatures over approximately 400 F. by increasing the amount of lithium hydroxyste'arate; whereas at lower temperatures the viscosity is increased by increasing the additive content.

This characteristic would be advantageous in coating applications, as for instance, mopping asphalts used on low slope or level roofs. This phenomena is illustrated in Example III by the recording of viscosities at 275 F. and 400 F. for various additive contents. Moreover, as illustrated in Example II, the flash point of the asphalt is increased upon the addition of lithium hydroxystcarate.

We claim:

1. An asphalt composition which consists essentially of a penetration grade petroleum asphalt having incorporated therein about 0.1 to 10% by weight of a lithium stearate to increase the softening point of the asphalt for a given penetration. I

2. The composition of claim 1 wherein the lithium stearate is lithium hydroxystearate.

3. An asphaltic composition which consists essentially of a penetration grade petroleum asphalt selected from the group consisting of oxidized and steam-vacuum refined asphalts having incorporated therein about 0.1 to 10% by weight of a lithium stearate to increase the softening point of the asphalt for a given penetration.

4. The composition of claim 3 wherein the lithium stearatc is lithium hydroxystearatc.

5. An asphalt composition which consists essentially of a penetration grade petroleum asphalt having incorporatcd therein about 0.1 to 10 percent by weight of lithium IZ-hydroxy stearate and in an amount suflicient to increase the softening point of the asphalt for a given penetration.

6. An asphaltic composition which consists essentially of penetration grade oxidized petroleum asphalt having incorporated therein about 0.1 to 10 percent by weight of a lithium stearate and in an amount suiiicient to increase the softening point of the asphalt for a given penetration.

7. The composition of claim 6 wherein the lithium stearate is lithium hydroxystearate.

8. An asphaltio composition which consists essentially of penetration grade oxidized petroleum asphalt having incorporated therein about 0.1 to 10 percent by weight of lithium 12-hydroxystearate and in an amount sufiicient to increase the softening point of the asphalt for a given penetration.

9. The composition of claim 4 wherein the lithium ste-arate is IZ-hydroxy stearate.

References Cited in the file of this patent UNITED STATES PATENTS 2,389,926 Morgan Nov. 27, 1945 FOREIGN PATENTS 404,939 Great Britain Jan. 18, 1934 

1. AN ASPHALT COMPOSITION WHICH CONSISTS ESSENTIALLY OF A PENETRATION GRADE PETROLEUM ASPHALT HAVING INCORPORATED THEREIN ABOUT 0.1 TO 10% BY WEIGHT OF A LITHIUM STEARATE TO INCREASE THE SOFTENING POINT OF THE ASPHALT FOR A GIVEN PENETRATION. 